Among these prior art instruments, apparatus, and processes are the following:
1. Instruments to measure sliver strength and/or "drag" during mechanical separation in the lengthwise direction. These are subject to large test errors, are time-consuming, and suffer from poor reproducibility and poor correlation with actual performance of the fiber in textile mills. In addition, it would be prohibitive timewise and costwise to test sufficient lengths of fiber to be representative of the entire lot of fiber. PA1 2. Devices to measure picker-lap strength. A picker is a machine which prepares a rolled mat of fibers to be unrolled in a controlled manner to supply fibers to a card. This method of supplying fibers requires extra labor to prepare the laps and to transport them to the cards. Pickers are now being replaced by the more efficient, chute-feed systems which supply fiber directly to the carding machine. Devices to measure lap strength are of limited value because the test responses are suitable for identifying only extremely strong versus extremely weak laps and, in addition, these devices are dependent to a significant degree upon the uniformity of the lap. The predictive value and reproducibility of lap-strength tests, which undesirably alter the crimp significantly, are not satisfactory in the range of cohesiveness of greatest importance that falls between the extremes. In addition, the industry is moving away from expensive and slow picker-lap preparation and toward chute-feeding machines which accomplish some opening of the fiber while delivering it to a chute which transmits the fiber directly to the card input without the costly process of lap preparation. PA1 3. Instruments and processes to measure the average of and/or variability in crimps per 2.54 centimeters (inch) and crimp angle of the staple fiber at some point prior to carding. These instruments and processes to measure crimps per 2.54 centimeters (inch) and angle are slow, time consuming, subject to large errors and have very poor predictive value concerning cohesiveness in the range of greatest importance between the extremes. Also, the relative contributions of a given combination of crimps per 2.54 centimeters (inch) and angle are difficult to measure. ASTM D-3937(13.2) states: "No justifiable statement can be made on the accuracy of Method D-3937 for testing crimp frequency since the true value cannot be established by an accepted referee method." PA1 4. Visual assessment of the web during carding to attempt to classify the web as "clear," "cloudy," "streaky," etc. These visual assessments of the carded web produce such a wide variety of judgments with such poor reproducibility for a given set of samples that little or no practical benefit is gained as far as fiber cohesiveness is concerned. PA1 5. Hand tests of the fiber removed from the bale to attempt to judge whether or not such handfuls fall apart easily, indicating low cohesion, or whether such samples of fiber exhibit greater resistance to falling apart when held elevated, indicating greater cohesiveness. Such hand tests are merely guesswork with very little practical benefit. Large differences in opinion are found among judges using hand tests. PA1 6. Maximum carding rate, which is a judgment of the greatest sustainable production rate in kilograms (pounds) per hour for a given fiber sample on a given card, has been used in an attempt to measure fiber cohesiveness. This test, however, suffers from wide variability from one card to another and from one operator to another in judging the end point at which the carded web just begins to sag or curl. At best, this time-consuming test provides only a rough estimate of differences in cohesiveness among different lots of staple fiber. The judgment of the maximum sustainable carding rate suffers particularly from wide variation in the zones of major interest between the extremes of low-cohesion reject and high-cohesion reject. Since this test is based on operator judgment and results vary from card to card, it must be used with caution and with full understanding that it provides only a rough estimate of differences in cohesion. It is not accurate enough for quality control. PA1 7. A colleague and I used air jet devices experimentally to blow with rising pressure at controlled rates into a carded web to create a bulge followed by attempts to determine by visual assessment at what air pressure the side walls of the bulge begin to create "open spaces" or "splits". This system suffered from poor reproducibility, however, due to wide variation among operators in guessing what constitutes an "open space" or "split." Poor results were obtained in tests with the jet mounted below the web and also in other tests in which the jet was mounted above the web. The location of the jet above the web was particularly poor in reproducibility and operation due to web collapses which made it necessary to clear the waste and rethread the card. These tests had poor correlation with actual carding perforance of the fiber in customers' mills and on our laboratory carding apparatus.
It was in the course of my own re-evaluation of this last experimental process or system described above that I discovered by accident an approach subsequently leading to the present invention. With the jet located below the web, I accidentally turned on too much air pressure, causing an unusually large bulge to form rapidly at this higher pressure followed quickly by an upward rupture of the top portion of the bulge. This ruptured portion of the bulge remained suspended in the stream of air in an upward position above the web and grew longer, up to 0.9 to 1.2 meters (three to four feet), as the carding machine continued to supply fiber in web form. The rupture resembled a long "tail" which was merely pulled harmlessly into the condensing guide along with the rest of the carded web and came out the other side of the condensing guide as part of the sliver. This proved to be a definite observable event for which an operator could readily say either that the bulge had ruptured into a tail or it had not so ruptured. I then began a systematic investigation and, after much trial and error, developed a dependable, reasonably precise operating method that correlates well with actual carding performance in customers' mills.